Generally, a sound device refers to a device from which sound is output, or a device to which sound is input.
Such sound devices are applied in various industrial fields such as computers, mobile electronic devices, medical equipment, and the like.
In recent years, mobile electronic devices such as portable terminals, digital cameras, notebooks, and the like are required to be waterproof sound devices capable of emitting or inputting sound while preventing water or dust from permeating into mobile electronic devices due to portability.
Meanwhile, a waterproof sound device is provided with a membrane that vibrates in order to transmit sound, and the performance of the waterproof sound device depends on the characteristics of the membrane, and thus development of an excellent membrane is required.
Korean Patent Application Publication No. 10-2009-0098566 discloses a method of manufacturing a hydrophilic and hydrophobic membrane, the method comprising: a template preparing step of preparing a template having fine holes formed on an outer surface thereof; a polymer material applying step of applying a polymer material to a predetermined pattern region on an outer surface of the template; a film attaching step of attaching a hydrophilic film to an outer surface of the template; and a template removing step of separating and removing the template from the hydrophilic film.
However, in Korean Patent Application Publication No. 10-2009-0098566, the template is removed to form nano-sized pillars in the polymer material, and the area where the nano-sized pillars are formed becomes a hydrophobic surface with minimal wettability. Therefore, there is a problem that the effective water repellency of the entire membrane is deteriorated because a technique of forming hydrophobicity only on the surface of the polymer material of the membrane is disclosed.
Korean Patent Application Publication No. 10-2010-0130796 discloses a technique of attaching a waterproof Gore-Tex (registered trademark of W. L. Gore and Associates) tape to a sound transmission hole of a cellular phone case to impart a waterproof function. However, this waterproof Gore-Tex tape which performs a waterproof function is attached to the cellular phone case. Therefore, there is a disadvantage that sound transmitted to the outside from the sound transmission hole or sound transmitted from the outside to the sound transmission hole is not smoothly transmitted.
Korean Patent Application Publication No. 10-2010-0046247 discloses an electroacoustic transducer including a case, a vibrating body provided in the case, a sound transmission hole and a sound transmission test hole formed in the case, and a waterproof film covering the sound transmission hole.
The waterproof membrane of Korean Patent Application Publication No. 10-2010-0046247 is also mounted on a frame having a sound transmission opening portion, and thus there is a problem that a sound transmission function is deteriorated.